Double vaccination can half risk of long COVID

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In a new study from King’s College London, researchers found Adults who have received a double vaccination are 49% less likely to have Long COVID should they contract a COVID-19 infection.

They analyzed data from participants logging their symptoms, tests and vaccines on the UK ZOE COVID Symptom Study app between 8th December 2020 and 4 July 2021, including 1,240,009 (first dose) and 971,504 (second dose) vaccinated UK adults.

The team assessed a range of factors, including age, frailty and areas of deprivation and compared that with post-vaccination infection.

They found that in the unlikely event of catching COVID-19 after being double vaccinated, the risk of Long COVID was reduced by almost half.

There were also fewer hospitalizations (73% less likely) and a lower burden of acute symptoms (31% less likely) among those fully vaccinated.

The nature of the most common symptoms was similar to unvaccinated adults – e.g. anosmia,(loss of smell) cough, fever, headaches, and fatigue.

All these symptoms were milder and less frequently reported by people who were vaccinated, and they were half as likely to get multiple symptoms in the first week of illness.

Sneezing was the only symptom that was more commonly reported in vaccinated people with COVID-19.

However, people living in most deprived areas were at greater risk of infection after a single vaccination.

While age on its own was not a risk factor, individuals who had health conditions that limited their independence – such as frailty – were up to two times more likely to contract COVID-19 infection after vaccination, and of getting sick.

The findings demonstrate the need to target at-risk groups. Frail adults have already been shown to be disproportionately affected by COVID-19.

The research team suggests strategies such as a timely booster program, targeted infection control measures and more research into the immune response to vaccination in this group could help address the issue.

The team says in terms of the burden of Long COVID, it’s good news that the research has found that having a double vaccination significantly reduces the risk of both catching the virus and if you do, developing long-standing symptoms.

However, among the frail, older adults and those living in deprived areas the risk is still significant and they should be urgently prioritized for second and booster vaccinations.

The study is published in the Lancet Infectious Diseases. One author of the study is Dr Claire Steves.

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